The ligand and redox states of iron and the roles of iron and sulfur in electron transport and in hydroxylation by P450 heme protein systems are explored with the P450 cam model for which the three pure protein components are available in gram quantities. Equilibrium measurements of asymmetric binding among enzyme components and with substrates to form quaternary (supramolecular) complexes provide the thermodynamic parameters of regulation. Rapid dynamic measurements, over the temperature range plus 40 to minus 40 degrees C, yield the rates of primary events, the accumulation of intermediates in accordance with their arrhenius coefficients, and their dependencies on carbon, oxygen and redox substrates. The influence of ligands and the ionic environment on the iron states, the confirmation of the heme pocket, and the stability of labile intermediates are thus available. The iron active centers of the enzymes are excellent reporter groups for a wide variety of resonance probes. The influence of protein is explored through structure modification by genetic mutants and chemical reagents to reveal structure-function relationships in catalysis and information of quaternary structures. The primary univalent redox processes of dioxygen reduction and of oxygenation can be generalized in sequence and oxygen effect for O2, H2O2, peracids, and aromatic iodoso-O. Consideration is also given to the importance of these systems to the maintenance of environmental quality, the detoxification of therapeutic drugs, crop protection chemicals and miscellaneous toxic substances of the environment, as well as to their persistence and mutogenic potential. More pertinent are the highly selective essential synthetic systems for the formation of the steroid and prostaglandin regulatory metabolites. BIBLIOGRAPHIC REFERENCE: Sligar, S. G. Namtvedt, M. J., Ellis, R. V., and Gunsalus, I. C. The Chemistry and Enzymology of Oxygenated Cytochrome P450. Hoppe-Seyler's Z. Physiol. Chem., 357, 1056, August 1976, ABSTRACT.